function deepDfs(node) {
    let result = [], index = 0
    function leavl(node, index) {
        if (!node) return
        if (!result[index]) result[index] = [];
        result[index].push(node.val)
        node.children.forEach(item => leavl(item, index + 1))
    }
    leavl(node, index)
    return result
}